One day in 1999, James Gandolfini walked down a driveway in a bathrobe, picked up the newspaper and changed television forever. If back then you were watching this new HBO drama with the title that seemed to be about opera, then you know how much talent the world lost when he died, suddenly and too soon, at age 51 on Wednesday (in Rome, of all places, where Tony Soprano sojourned in the show’s second season). But with his forceful, charismatic, yet subtle performance as a suburban mobster, Gandolfini changed the TV you watched even if you’ve never watched a minute of The Sopranos.

Because without Gandolfini, there would be no Tony — not as we know him. And without Tony, there would be no Walter White, no Vic Mackey, no Carrie Mathison. Through Tony, Gandolfini wrote the blueprint for the modern, complicated TV antihero; he took the wall between stand-up TV good guys and wicked bad guys and bashed it down with a baseball bat.

And without The Sopranos, becoming a smash pop-culture phenom by telling an incredibly sophisticated story, it’s hard to imagine Deadwood, The Americans, or dozens of other ambitious dramas that came after; it’s hard to imagine the now widespread belief that TV could be art. Without the made men, no Mad Men (whose creator, Matthew Weiner, apprenticed writing for The Sopranos). “Lately,” said Tony in one of his early scenes with his therapist, Dr. Melfi, “I’m getting the feeling I came in at the end.” Gandolfini, on the other hand, got in on something on the ground floor.

He very nearly didn’t: at various points in The Sopranos’ conception, Anthony LaPaglia was considered for Tony, as was Steve Van Zandt (who ended up taking the more comic-dramatic role of consigliere Silvio Dante). But as creator David Chase told Vanity Fair in an oral history of the show last year, “when Jim Gandolfini walked in, that was it.”

Boy, was it. Yes, to look at him, Gandolfini was just the kind of guy you might cast for a New Jersey titan of “waste management,” bullheaded and terrifying and thus all the more ironic when squinched into a therapist’s-office chair. If that had been all there was to him, The Sopranos might have been a simpler, though entertaining, show. But Gandolfini immediately brought so much more to life in Tony: his intelligence, his sadness, his fear, his self-pity, his mama’s-boy wrath. Yes, he could kill a man in a bathtub convincingly, but he just as easily could sit at a family dinner and chafe against his own skin, and make you feel a lifetime of pinpricks, many self-inflicted, stabbing him from the inside.

His was an amazingly delicate performance for a big guy. Those eyes. Gandolfini could concentrate all of Tony’s physicality and criminal cunning into them, as those black pellets darted about and he conceived a lie to tell Carmela, or a way out of a business bind. That a man with such a hulking physicality — a presence that was itself essential to the character — could convey so much through such minute gestures was like watching a giant sit and play a virtuosic Goldberg Variations on a toy piano.

Gandolfini’s performance as Tony, in fact, was so rich, so effective, that it sometimes had unintended consequences. Some fans came to love Tony, to cheer for him, or at least become thrilled by his exploits; they followed the show to see who would get whacked or how Tony would extricate himself from his troubles with Phil Leotardo. In the final season, Chase dialed up the darkness in his antihero, and Gandolfini responded with a run of work that was the greatest thing on TV since — since, well, the first season of The Sopranos.

Snuffing the life out of his own nephew, looking trippily at a desert sunrise and shouting with smug self-delusion, “I get it!” — Gandolfini made the emptiness at the core of Tony something you could weigh on a scale. And yet we couldn’t just write Tony off and distance ourselves. We were in too deep with him. It would have been an easy thing for Gandolfini to make us fear Tony Soprano. It would have been a neat parlor trick to make us love him. James Gandolfini — in sync with Chase and a peerless cast of co-stars — made us understand Tony, in all his pathetic, charismatic devilry. And that was the work of an artist.

Tony Soprano was not all there was to Gandolfini. Typecasting may have kept him from getting movie work commensurate with his small-screen greatness, but he disappeared in roles from drama to comedy to fantasy: Zero Dark Thirty, Where the Wild Things Are, Chase’s own Not Fade Away. But if it was TV that used him best, that’s only appropriate. He ushered in, practically created, not just an era of really good TV shows, but an idea: that TV could be as rich, great, relevant, moving, conversation-driving and significant as any contemporary movie or even novel.

(And it mattered, by the way, that Gandolfini was ridiculously entertaining: fun, compelling, thrilling. To change TV, The Sopranos needed to be a huge commercial hit as much as it needed to be a work of genius. The scripts put ideas in our heads, but it was Tony who put butts on couches.)

James Gandolfini was our usher into that new TV era, by taking a performance that could have been cartoonish (remember Analyze This?) and making it psychologically layered and unshakeable. This was a man who could show us a brute throttling a Mafia turncoat while looking at colleges with his daughter and make us think: I want to know this guy better. He could lead us, mildly contemplating an onion ring, to the finale’s famous cut-to-black, to the tune of “Don’t Stop Believin’,” and leave us wondering whether he lived or died, and what he deserved, and what it all meant.

We can only wonder what more Gandolfini would have done with a more fair measure of years. “He was special man, a great talent,” read an HBO statement, “but more importantly a gentle and loving person who treated everyone no matter their title or position with equal respect. He touched so many of us over the years with his humor, his warmth and his humility.” Chase paid him touching tribute: “A great deal of that genius resided in those sad eyes. I remember telling him many times, ‘You don’t get it. You’re like Mozart.’ There would be silence at the other end of the phone … He wasn’t easy sometimes. But he was my partner, he was my brother in ways I can’t explain and never will be able to explain.”

Like that final scene, Gandolfini’s potential was cut short. But his accomplishment, and the way he expanded the possibilities of his medium and his craft: it goes on and on and on and on. RIP.